Using NOT WORKING CORRECTLY ok for Megadrive controllers with HyperSpin. The Analogic direction are not usable but few buttons can be used (strange behavior !)Using ok for SNES controllers with HyperSpin

d) Mame32

You must use TAB key to define controller mapping when a game is launched (Joystick option selected previously into the Mame32 interface)

Possible to do mapping with SNES controllers (it rocks because all buttons are usable !!!)Impossible to do mapping with Megadrive controllers

This all sounds like more of a software problem than something that should be fixed on the Retrode's side. Felix is right - you should definitely try Keyboard Mode, which maps the Sega controllers to the same keys as SNES controllers. You will lose 4-player functionality but it is probably the most compatible mode.